A project for S. P. Richards Company

The company and its DC operations

Click to enlarge.

Small parts stored in 18-inch deep shelves.

SPR distributes wholesale office products. Each DC accepts orders until 5PM and ships overnight for next day delivery. Orders are received, filled, and shipped on the same day.

There are three distinct picking zones: palletized product, light bulk, and small parts. We will be concerned with small parts, which are picked manually into totes. The totes then are placed on a conveyor to packing stations.

The warehouse management system used by SPR examines each customer order, converts order-lines to pick-lines, and assigns the pick-lines to a set of boxes. All the items assigned to a box are picked together. The packer then prepares the recommended boxes and fills them with their assigned items plus dunnage. An efficient packing will use fewer boxes, with each (nearly) filled.

Here is a copy of the class presentation by SPR representatives.

The project

  1. Given its current cubing algorithm, what box sizes should SPR stock? Should the same sizes be used at all DCs? Or can all DCs standardize on the same set of sizes?
  2. Can the current cubing algorithm be improved? An effective algorithm must account for the following:

Miscellaneous notes:


The company data is copyrighted and proprietary. You may use it for the purposes of this course only. (If you would like to use it for something else, please contact me to discuss.)

The warehouse management system (WMS) assigns virtual cartons (that is, sets of pick-lines) to carts sufficient to (nearly) fill the capacity of the cart, which is approximately 13,000 cubic inches. This assignment is guided by logic such as this: Assume zones A and B are on the mezzanine and zones C and D are downstairs, on the ground floor. Then the WMS may assign picks to carts according to the following logic: Group together cartons (sets of pick-lines) that have similar extent in the warehouse. More specifically, Group together cartons that

Each group of cartons (sets of picks) that have similar extent would be assigned to the same cart, as much as possible.

Here are the zones in which small parts are stored:

The client suggests assuming that air pillows are used for dunnage in parcel orders and that paper is used for non-parcel orders. The use of air pillows is roughly proportional to the length of the longest dimension of a box; the use of paper is roughly proportional to the unoccupied volume in a box. A reasonable price for air pillows would be $80 per roll, with the roll being 2900-feet in length and the pillows perforated every 8 inches. Paper dunnage comes in a number of different sizes and shapes. A typical version would be a roll 36-inches wide by 1,500 feet long at $17 per roll.

Suggested first steps